Wu L, Banuelos G, Guo X
Department of Environmental Horticulture, United States Department of Agriculture-Agricultural Research Service, Water Management Research Laboratory, University of California, 2021 S. Peach Avenue, Davis, California, 95616, USA.
Ecotoxicol Environ Saf. 2000 Oct;47(2):201-9. doi: 10.1006/eesa.2000.1948.
A field survey was conducted in 1989, 1994, and 1999 in order to monitor the soil and vegetation Se concentrations at the Kesterson upland grassland contaminated by Se-rich drainage sediment. The rate of Se dissipation estimated by the change of soil Se concentration, via volatilization, found to be about 1.1% per year. Soil water-extractable Se increased in 1994, but greatly reduced in 1999. The increase of soil Se concentration in the top 15 cm of soil at the fresh-soil fill sites indicates that the plants were able to effectively take up the soluble soil Se from the lower soil profile and to deposit it on the top of the field. This process may reduce the rate of leaching of soil Se. Overall, the concentration of soil water-soluble Se was relatively low and it is unlikely that problems of transport of Se from the Kesterson soil to the adjacent uncontaminated environment by leaching can occur. Plant tissue Se concentration was found to coincide with the soil water-extractable Se concentration. The average plant tissue Se concentration and soil water-extractable Se detected in 1999 was about 10 microg Se g(-1) and 110 microg Se kg(-1) dry weight, respectively, and the estimated bioaccumulation value of this upland grassland is less than 10% of the previous wetland habitat. Therefore, the existing Kesterson grassland should not be at high risk to the environment.
为监测受富含硒的排水沉积物污染的凯斯特森高地草原土壤和植被中的硒浓度，分别于1989年、1994年和1999年进行了实地调查。通过土壤硒浓度变化估算出的硒挥发消散速率约为每年1.1%。1994年土壤可水提取硒增加，但1999年大幅下降。新鲜土壤填充点土壤表层15厘米处土壤硒浓度的增加表明，植物能够有效地从较低土壤剖面吸收可溶性土壤硒并将其沉积在田地顶部。这一过程可能会降低土壤硒的淋溶速率。总体而言，土壤水溶性硒浓度相对较低，不太可能出现硒从凯斯特森土壤通过淋溶转移到相邻未受污染环境的问题。发现植物组织硒浓度与土壤可水提取硒浓度一致。1999年检测到的植物组织平均硒浓度和土壤可水提取硒分别约为10微克硒/克（干重）和110微克硒/千克（干重），该高地草原的估计生物累积值不到先前湿地栖息地的10%。因此，现有的凯斯特森草原对环境的风险应该不高。
